Sound producing diaphragm and method of making same



Aug. 16, 1932 J. B. HAWLEY 1,372,533

SOUND PRODUCING DIAPHRAGM AND METHOD .OF MAKING SAME Filed 001:. 20.1930 Patented Aug. 16, 1932 UNITED srA'r-ss PATENT OFFICE JESSE H. mm,OF GENEVA, ILLINOIS SOUND PRODUCING DIAPHRAGM AND METHOD MAKING sumApplication filed October 20, 1930. Serial No. 489,835.

Among the objects of the invention is to provide a novel sound producingor reproducmg diaphragm or diaphragmatic memher and a novel method ofmaking or producmg 1t.

To obtain a sound producing or reproduclng diaphragm capable ofproducing or reproducing sound true and faithful to the original soundto be reproduced, it is necessary that the diaphragmatic member be aslight in weight as possible, and not subject to a natural period orfundamental frequency, yet sufliciently stiif to set up the proper wavesin the sound medium.

An object of this invention is to produce such a sound producer orreproducer which will have a substantially even response curve where allsounds of the audible range will be produced or reproduced withsubstantial- 1y equal efliciency.

In an illustrative embodiment of the in vention, the sound producer ispreferably of molded fibrous material. It is made in one integral pieceand without any seam. It

may be of cone shape with an integral basal flange by which the conemaybe. supported. It is very thin and very light in' weight to reduce toa minimum, the mass inertia or momentum thereof. The flange ispreferably made with a border portion for retention by a support orholding means, and a thinner portion between the border portion and thebody or cone part of the device, whereby the freedom of vibration of thesound producer may be atly enhanced, the thinner portion mentloned beinvery easily flexed or having increased exure. This thinner portion maybe efiected by in- .terposing a blanking member or stopper ring D on thepartly formed and molded fibrous blank during the molding process, tostop further deposit of fibres under said ring while further fibres arebeing deposited in p the completion of the remainder of the article.

Another object of the invention is to impregnate the sound producer withmoisture or water proofing material or substance, whereby the acousticproperties of the diaphragm will not change with the humidity of thesound medium, such as the air of the atmosphere. The impregnation may beof different degrees over the diaphragm, so that different parts of thediaphragm may be efiiciently responsive to the different periods of theaudible range of sound to the end of making the diaphra m substantiallynon-fundamental in period.

A further object is to provide a novel process of making such adiaphragm as by deositing the fibres of a bath on a orous ormer,interposing a blanking mem r or stopper on the part of the fibrous blankto be left thin, impregrating the blank, and finishinkg it, as bydrying, compressing, and the Other objects, advantages, capabilities,features and rocess steps are comprehended by the invention as willlater appear and as are inherently possessed thereby.

Referring to the drawing;

Fig. 1 is a vertical sectional view through a former and a partly moldedfibrous blank.

Fi 2'is a similar view showin the interposition of the stopper ring anthe completed blank.

Fig. 3 isa top plan view of the means shown in Fig. 2.

Fi 4 is a sectional view of a completed soun reproducer; and

Fig. 5 is-a fragmentary sectional view of an alternate form.

Referring now more in detail to the drawing, the diaphragm of thisinvention is made by depositing fibres upon a porous'former 1 havingpores or apertures 2, from a bath of fibrous material and a liquid suchas water. The former 1 as in the illustrative construction, is of coneshape and has a closed or nonporous cap 3, and a flange 4,;wh1ch isporous. This former ma fit into a container 5 of the bath. Withm andbelow the former a artial vacuum is created so that the liquid of thefibrous bath may be sucked throu h the pores 2 of the former and cause aep osit of fibres 6 upon the former as shown m '%he former 1 may alsohave a curved portion 7 so as to form a corrugation 8 1n the fibrousblank 6 being formed on the former.

After there has been a partial deposit of the fibres upon the former, ablanking or stopping ring 9 may be positioned over the flange portion 10of the blank to stop further deposit of the fibres at the area 11 whenfurther fibres are being deposited upon the former to efiect the finallymade blank 1" as clearly shown in Fig. 2. This leaves a thin fibrousportion 11 between the border portion 12 of the flange 10, and thejuncture between the cone 1' and said flange. The juncture 13 betweenthe cone and the thin portion 11 may be slightly thicker than theremainder of the blank, to strengthen the blank at such point.

If desired the juncture may be made thin and formed with a double corruation 14 as shown in Fig. 5 and connected etween the thin portion 11 andthe corrugation 14, as clearly indicated in that figure. This aids inthe fiexure between the border 12 and the cone 1". After the blank isformed it may be removed from the former and placed upon a similarformer for finishing, or the original former with the blank may beremoved to a finishing machine. In a finishin process, hot air may besucked through the lank and the sup orting porous member so as to drythe fibrous lank. If desired, the blank may also be com ressed. This maybe done either mechanically or by increasing the suction on one side ofthe holder for the blank and the pressure of the hot air on the otherside. In

this way the fibres may be more compact.

It is preferable to treat the blank with some impregnating materialwhich has moisture or water proo ng properties. As for example, theapical or central portion of the diaphragm or cone may be impregnated asby dipping or spraying with such substances as duco, lacquer or likesimilar substances. The remainder of the diaphragm may be impregnatedwith such substances as rubber-cement or other water proofing materialso that this part of the diaphragm will be more supple or limber thanthe central portion of the diaphragm. The central portion of thediaphragm is preferably impregnated with a denser substance so that suchcentral portion will be stiffer than the remainder of the diaphragm. Thebasal flange portion may be impregnated with such material as rubbercement, latex and other =like and similar materials. The impregnationsmay vary over different areas so that the stifl'ness and flexibility mayvary accordingly.

' If desired, the impregnating material might be mixed in the pulp bathso that as the fibres are deposited, they will also carry with them theproofing material. Such material as asphaltum, latex, resin size andsulphate of aluminum may be used. These may help to toughen andwaterproof the material of the diaphragm so that the diaphragm will havethe desired acoustic characteristics mentioned above. Any kind of fibremay be used.

The diaphragm is of extremely light weight and very flexible in theflange portion thereo particularly at the thin portion 11. In use a.hollow cylinder is attached to the neck-15 and carries a coil of finewire located in an annular magneticgap of an electrodynamic type ofactuator.

The border 12 is claniped in a fixed part of the sound reproducermechanism, so that the diaphragm or cone is suspended by way of the thinband 11. Suitable means, as usually used may be used at the neck portion15 for movably supporting that end.

As the cone portion is vibrated, the thin band 11 permits its freedom ofvibration by 'reason of the thinness of the portion 11 and itsflexibility. This may be aided by providing one or more corrugations 14or even a single corrugation such as that formed at 8 as shown in Fig.1.

One of the difiiculties met with in this art, is that a. diaphragm ofthis kind usually has some fundamental period or natural frequency ofvibration at which some waves of the same period will bemore-efiiciently rendered or reproduced than the others of the audiblerange. In making a portion of the diaphragm stiffer than anotherportion, certain frequencies of the audible range will be moreefiiciently transmitted or emitted by the stiffer portion, while theother frequencies will be more efliciently transmitted by the less stiffportion of the diaphragm. As for example, if the diaphragm be of lownatural period tendency, it would tend to reproduce low frequencies moreefiiciently. By stiffening a portion, that portion will transmit certainfrequencies, such as the high frequencies more efliciently, and bymaking other portions more flexible, the latter portion will transmitother frequencies such as low frequencies, more efficiently. In this waythe wholeaudible range may be efliciently reproduced.

By making the diaphragm of integral material, such as molded fibroussubstances, certain disadvantages are avoided, such as those that arepresent in the rolled and seamed cone, or the stretched cone. In thelatter forms, the material used is placed under strains and stresseswhich affect the acoustic properties of the sound reproducer. By thepresent invention, the shape of the diaphragm is that originallyproduced and there is no strain nor stress of any kind to afi'ect itsacousticproperties. The diaphragm of the present invention is more orless porous even after it is impregnated and its porosity seems to havethe characteristic of engaging-the sound transmitting medium without anytendency of slippage and hence loss of sound re reduction;

ile I have herein described and upon the drawing disclosed an embodimentof the invention and a process of producing it, it is to be understoodthat the invention is not limited thereto but may comprehend otherdetails, arrangement of parts, details, features and process stepswithout departing from the spirit thereof.

Having 5 thus disclosed the I claim:

1. A sound roducer of integral molded fibrous material comprising a bodyportion and a base portion, said base portion having a part of lessthickness than the remainder of the producer forenhancing the freedom ofvibration of the producer.

2. A sound reproducing seamless diaphragm, initially formed integrallythroughout of accretions of 'fibrous material, comprisinga cone shapedbody and a basal flan' e, said flange having a thing annular area orincreasing the flexure of the flange portion.

3. A sound reproducing diaphragm comprising a cone-shaped body, anannular flange and an annular integral juncture between the body and theflange, said body, juncture and invention,

flange being composed of deposited fibrous pulp the fibres of which havebeen initially deposited in the form of said body, juncture and flange,said fibres being arran ed in interlaced accretions and normally ree ofinternal stresses which may tend to change the form or shape of thediaphragm as originally formed, said juncture be1n thinner than saidbody and acting to permit the free and unimpeded vibratile action ofsaid body when generating sound but at the same time supporting saidbody for a balanced vibration thereof.

4. A sound reproducing diaphragm comprisin a cone-shaped body, anintegral annular asal juncture and an integral basal flange, allcomposed of accretions of interlaced fibres which have been initiallydeposited in the form of the body, juncture and flange, said body andjuncture being normally free of internal stresses that would tend tochange the form or shape of said body and juncture as originally formed,the fibres of the body and juncture being arranged to provide a cellular,construction therein, the body being of substantially uniform thicknessin.

6. A sound producer composed of integral molded fibrous material andcomprising a diaphragmatic member impregnated with moisture proofmaterial.

7. A sound producer composed of integral molded fibrous material andcomprising a diaphragmatic member impregnated with moisture proofmaterial, the central portion of said member being more denselyimpregnated to-give said portion greater sti ness than the remainder ofsaid member.

8. A sound producer, comprising a diaphragmatic member impregnated withmoisture proof material, the central portion of said member beingimpregnated with a denser material than the remainder of said member togive said central portion greater stiffness than the remainder of saidmember.

a 9. A sound producer composed of integral molded fibrous material andcomprising a. cone portion and a flange portion, said flange portioncomprising a border and a supporting portion between the cone portionand the order portion, said supporting portion being thinner than theremainder of the producer.

10. In a process of making molded fibrous diaphragmatic sound producers,the steps of forming a blank on a porous former, and placing a stopperon a portion of the blank during its forming to leave the portion of theblank under said stopper thinner than the remainder of the blank.

'11. In a process oi making molded fibrous diaphragmatic soundproducers, the steps of forming a blank on a porous former, placing astopper on a portion ofthe blank during its formin to leave the portionof the blank under said stopper "thinner than the remainder of theblank, and drying the blank.

12. Ina process of making molded fibrous diaphragmatic sound producers,the steps of forming a blank on a porous former, placing a stopper on aportion of the blank durin its formin to leave the portion of the blanunder said stopper thinner than the remainder of the blank, andimpregnating th blank with moisture proofing material.

13. In a process of making molded fibrous diaphragmatic sound producers,the steps of orming a blank on a porous former, placing a'stopper on aportion of the blank during its formin to leave the portion of the blankunder sald stopper thinner than the remainder of the blank, impregnatingthe central ortion of said blank with a moisture proo ng and stiffeningsubstance, and impregnating the remainder of said blank with a moistureproofing supple producing substance.

14. A sound reproducing seamless diaphragm, initially formed integrallythroughout of accretions of fibrous material comprising a vibratile coneshaped body, and an annular flange having a pliant juncture integrallyconnecting the body and flange, said juncture bein of thinner materialthan said cone shaped 'dy and acting to permit the free and unim ededvibratile action of the cone shaped body when generating sound but atthe same time'supportin'g said body for a balanced vibration thereof.

15. A sound reproducing seamless diaphra initially formed integrallythroughout o d ccretions of fibrous material, compris- 11:5 :1 vibratilecone shaped body, and an ann ar flange havin a pliant junctureintegrally connectin 51o body and flange, said Juncture being 0 thinnermaterial than said cone shaped body and undulated in form and acting topermit the free and unimpeded vibrati e action of the cone shaped bodywhen generating sound but at the same time supporting said body for abalanced vibration thereof.

In witness whereof, I hereunto subscribe my name to this specification.

JESSE B. HAWLEY.

CERTIFICATE OF (iORREGTlON.

Patent No. 1,872,583.

ms sa B; aawuar.

August 16, 1932.

lt is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 3,Ime ZiJ, claim; 2, for "thing" read "thin"; and line 64, claim 5; for"a" read the and that the said Letters Patent should be read with thesecorrections therein that the same may conform to the record of the casein the Patent Office.

Signed and sealed this 29th day of November, A. D. 1932.

J. Moore, Actingflommissloner of Patents.

juncture bein of thinner material than said cone shaped 'dy and actingto permit the free and unim eded vibratile action of the cone shapedbody when generating sound but at the same time'supportin'g said bodyfor a balanced vibration thereof.

15. A sound reproducing seamless diaphra initially formed integrallythroughout o d ccretions of fibrous material, compris- 11:5 :1 vibratilecone shaped body, and an ann ar flange havin a pliant junctureintegrally connectin 51o body and flange, said Juncture being 0 thinnermaterial than said cone shaped body and undulated in form and acting topermit the free and unimpeded vibrati e action of the cone shaped bodywhen generating sound but at the same time supporting said body for abalanced vibration thereof.

In witness whereof, I hereunto subscribe my name to this specification.

JESSE B. HAWLEY.

CERTIFICATE OF (iORREGTlON.

Patent No. 1,872,583.

ms sa B; aawuar.

August 16, 1932.

lt is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 3,Ime ZiJ, claim; 2, for "thing" read "thin"; and line 64, claim 5; for"a" read the and that the said Letters Patent should be read with thesecorrections therein that the same may conform to the record of the casein the Patent Office.

Signed and sealed this 29th day of November, A. D. 1932.

J. Moore, Actingflommissloner of Patents.

